Longitudinal Imaging of the Premalignant Tumor Microenvironment Reveals Transient Myeloid States Predictive of Tumor Fate

The spontaneous regression of cancer lesions illustrates the power of immune surveillance; yet these transient events have largely escaped systematic analysis. Using longitudinal intravital microscopy in a carcinogen-induced model of head and neck cancer, we followed premalignant lesions within the same animals for 24 weeks at single-cell resolution. This strategy uncovered three trajectories: progression, stability, or regression, and enabled direct analysis of immune dynamics underlying each fate. Lesion outcome was determined by the spatial organization of myeloid-derived antigen-presenting cells: regressing lesions were characterized by dense clusters of myeloid-derived cells associated with CXCL9+/CXCL10+ expression and T cell recruitment, whereas progressing lesions displayed a scattered infiltration of these cells. Remarkably, transient myeloid clusters arose prior to any detectable lesion formation and marked regions that would later develop into premalignant lesions. These findings identify spatiotemporal myeloid organization as an early determinant of tumor fate and provide a mechanistic framework for predicting and intercepting cancer at its inception. Summary SentenceEarly myeloid architecture dictates cancer fate: dense CXCL9/CXCL10 clusters with T-cell enrichment accompany regression, whereas sparse infiltration predicts progression. Transient pre-lesional myeloid clusters emerge at future tumor sites, revealing immune organization as an early determinant of malignancy.